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  • Why doesn't this CompiledQuery give a performance improvement?

    - by Grammarian
    I am trying to speed up an often used query. Using a CompiledQuery seemed to be the answer. But when I tried the compiled version, there was no difference in performance between the compiled and non-compiled versions. Can someone please tell me why using Queries.FindTradeByTradeTagCompiled is not faster than using Queries.FindTradeByTradeTag? static class Queries { // Pre-compiled query, as per http://msdn.microsoft.com/en-us/library/bb896297 private static readonly Func<MyEntities, int, IQueryable<Trade>> mCompiledFindTradeQuery = CompiledQuery.Compile<MyEntities, int, IQueryable<Trade>>( (entities, tag) => from trade in entities.TradeSet where trade.trade_tag == tag select trade); public static Trade FindTradeByTradeTagCompiled(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = mCompiledFindTradeQuery(entities, tag); return tradeQuery.FirstOrDefault(); } public static Trade FindTradeByTradeTag(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = from trade in entities.TradeSet where trade.trade_tag == tag select trade; return tradeQuery.FirstOrDefault(); } }

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  • Javascript, IE, Strings, and Performance problems

    - by Infinity
    Hey guys, So we have this product, and it's really slow in IE. We've already applied a lot of the practices advised by the IE guys themselves (like this, and this), and try to sacrifice clean code for performance in the critical parts like DOM manipulation. However, as you can see in this IE profiler screenshot.. Just "String" is the biggest offender. Almost 750ms of exclusive time. Does this mean IE is spending 750ms just instantiating Strings? I also read this stuff on the Opera dev blog: A build script can remove whitespace, comments, replace strings with Array lookups (to avoid MSIE creating a string object for every single instance of a string — even in conditions) But no more info regarding this. Anyone can clarify? It seems like IE has to create a full String instance every time you have " " in your code, which could explain this, but I don't know what the array lookup optimization would look like. BTW- we don't really do much of string concatenation anywhere in the code. The library we use is MooTools 1.2.4 Any suggestions will be appreciated! Thx

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  • Performance when querying a View

    - by Nate Bross
    I'm wondering if this is a bad practice or if in general this is the correct approach. Lets say that I've created a view that combines a few attributes from a few tables. My question, what do I need to do so I can query against this view as if it were a table without worrying about performance? All attributes in the original tables are indexed, my concern is that the result view will have hundreds of thousands of records, which I will want to narrow down quite a bit based on user input. What I'd like to avoid, is having multiple versions of the code that generates this view floating around with a few extra "where" conditions to facilitate the user input filtering. For example, assume my view has this header VIEW(Name, Type, DateEntered) this may have 100,000+ rows (possibly millions). I'd like to be able to make this view in SQL Server, and then in my application write querlies like this: SELECT Name, Type, DateEntered FROM MyView WHERE DateEntered BETWEEN @date1 and @date2; Basically, I am denormalizing my data for a series of reports that need to be run, and I'd like to centralize where I pull the data from, maybe I'm not looking at this problem from the right angle though, so I'm open to alternative ways to attack this.

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  • Performance issues when using SSD for a developer notebook (WAMP/LAMP stack)?

    - by András Szepesházi
    I'm a web application developer using my notebook as a standalone development environment (WAMP stack). I just switched from a Core2-duo Vista 32 bit notebook with 2Gb RAM and SATA HDD, to an i5-2520M Win7 64 bit with 4Gb RAM and 128 GB SDD (Corsair P3 128). My initial experience was what I expected, fast boot, quick load of all the applications (Eclipse takes now 5 seconds as opposed to 30s on my old notebook), overall great experience. Then I started to build up my development stack, both as LAMP (using VirtualBox with a debian guest) and WAMP (windows native apache + mysql + php). I wanted to compare those two. This still all worked great out, then I started to pull in my projects to these stacks. And here came the nasty surprise, one of those projects produced a lot worse response times than on my old notebook (that was true for both the VirtualBox and WAMP stack). Apache, php and mysql configurations were practically identical in all environments. I started to do a lot of benchmarking and profiling, and here is what I've found: All general benchmarks (Performance Test 7.0, HDTune Pro, wPrime2 and some more) gave a big advantage to the new notebook. Nothing surprising here. Disc specific tests showed that read/write operations peaked around 380M/160M for the SSD, and all the different sized block operations also performed very well. Started apache performance benchmarking with Apache Benchmark for a small static html file (10 concurrent threads, 500 iterations). Old notebook: min 47ms, median 111ms, max 156ms New WAMP stack: min 71ms, median 135ms, max 296ms New LAMP stack (in VirtualBox): min 6ms, median 46ms, max 175ms Right here I don't get why the native WAMP stack performed so bad, but at least the LAMP environment brought the expected speed. Apache performance measurement for non-cached php content. The php runs a loop of 1000 and generates sha1(uniqid()) inisde. Again, 10 concurrent threads, 500 iterations were used for the benchmark. Old notebook: min 0ms, median 39ms, max 218ms New WAMP stack: min 20ms, median 61ms, max 186ms New LAMP stack (in VirtualBox): min 124ms, median 704ms, max 2463ms What the hell? The new LAMP performed miserably, and even the new native WAMP was outperformed by the old notebook. php + mysql test. The test consists of connecting to a database and reading a single record form a table using INNER JOIN on 3 more (indexed) tables, repeated 100 times within a loop. Databases were identical. 10 concurrent threads, 100 iterations were used for the benchmark. Old notebook: min 1201ms, median 1734ms, max 3728ms New WAMP stack: min 367ms, median 675ms, max 1893ms New LAMP stack (in VirtualBox): min 1410ms, median 3659ms, max 5045ms And the same test with concurrency set to 1 (instead of 10): Old notebook: min 1201ms, median 1261ms, max 1357ms New WAMP stack: min 399ms, median 483ms, max 539ms New LAMP stack (in VirtualBox): min 285ms, median 348ms, max 444ms Strictly for my purposes, as I'm using a self contained development environment (= low concurrency) I could be satisfied with the second test's result. Though I have no idea why the VirtualBox environment performed so bad with higher concurrency. Finally I performed a test of including many php files. The application that I mentioned at the beginning, the one that was performing so bad, has a heavy bootstrap, loads hundreds of small library and configuration files while initializing. So this test does nothing else just includes about 100 files. Concurrency set to 1, 100 iterations: Old notebook: min 140ms, median 168ms, max 406ms New WAMP stack: min 434ms, median 488ms, max 604ms New LAMP stack (in VirtualBox): min 413ms, median 1040ms, max 1921ms Even if I consider that VirtualBox reached those files via shared folders, and that slows things down a bit, I still don't see how could the old notebook outperform so heavily both new configurations. And I think this is the real root of the slow performance, as the application uses even more includes, and the whole bootstrap will occur several times within a page request (for each ajax call, for example). To sum it up, here I am with a brand new high-performance notebook that loads the same page in 20 seconds, that my old notebook can do in 5-7 seconds. Needless to say, I'm not a very happy person right now. Why do you think I experience these poor performance values? What are my options to remedy this situation?

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  • Database Rebuild

    - by Robert May
    I promised I’d have a simpler mechanism for rebuilding the database.  Below is a complete MSBuild targets file for rebuilding the database from scratch.  I don’t know if I’ve explained the rational for this.  The reason why you’d WANT to do this is so that each developer has a clean version of the database on their local machine.  This also includes the continuous integration environment.  Basically, you can do whatever you want to the database without fear, and in a minute or two, have a completely rebuilt database structure. DBDeploy (including the KTSC build task for dbdeploy) is used in this script to do change tracking on the database itself.  The MSBuild ExtensionPack is used in this target file.  You can get an MSBuild DBDeploy task here. There are two database scripts that you’ll see below.  First is the task for creating an admin (dbo) user in the system.  This script looks like the following: USE [master] GO If not Exists (select Name from sys.sql_logins where name = '$(User)') BEGIN CREATE LOGIN [$(User)] WITH PASSWORD=N'$(Password)', DEFAULT_DATABASE=[$(DatabaseName)], CHECK_EXPIRATION=OFF, CHECK_POLICY=OFF END GO EXEC master..sp_addsrvrolemember @loginame = N'$(User)', @rolename = N'sysadmin' GO USE [$(DatabaseName)] GO CREATE USER [$(User)] FOR LOGIN [$(User)] GO ALTER USER [$(User)] WITH DEFAULT_SCHEMA=[dbo] GO EXEC sp_addrolemember N'db_owner', N'$(User)' GO The second creates the changelog table.  This script can also be found in the dbdeploy.net install\scripts directory. CREATE TABLE changelog ( change_number INTEGER NOT NULL, delta_set VARCHAR(10) NOT NULL, start_dt DATETIME NOT NULL, complete_dt DATETIME NULL, applied_by VARCHAR(100) NOT NULL, description VARCHAR(500) NOT NULL ) GO ALTER TABLE changelog ADD CONSTRAINT Pkchangelog PRIMARY KEY (change_number, delta_set) GO Finally, Here’s the targets file. <Projectxmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="4.0" DefaultTargets="Update">   <PropertyGroup>     <DatabaseName>TestDatabase</DatabaseName>     <Server>localhost</Server>     <ScriptDirectory>.\Scripts</ScriptDirectory>     <RebuildDirectory>.\Rebuild</RebuildDirectory>     <TestDataDirectory>.\TestData</TestDataDirectory>     <DbDeploy>.\DBDeploy</DbDeploy>     <User>TestUser</User>     <Password>TestPassword</Password>     <BCP>bcp</BCP>     <BCPOptions>-S$(Server) -U$(User) -P$(Password) -N -E -k</BCPOptions>     <OutputFileName>dbDeploy-output.sql</OutputFileName>     <UndoFileName>dbDeploy-output-undo.sql</UndoFileName>     <LastChangeToApply>99999</LastChangeToApply>   </PropertyGroup>     <ImportProject="$(MSBuildExtensionsPath)\ExtensionPack\4.0\MSBuild.ExtensionPack.tasks"/>   <UsingTask TaskName="Ktsc.Build.DBDeploy" AssemblyFile="$(DbDeploy)\Ktsc.Build.dll"/>   <ItemGroup>     <VariableInclude="DatabaseName">       <Value>$(DatabaseName)</Value>     </Variable>     <VariableInclude="Server">       <Value>$(Server)</Value>     </Variable>     <VariableInclude="User">       <Value>$(User)</Value>     </Variable>     <VariableInclude="Password">       <Value>$(Password)</Value>     </Variable>   </ItemGroup>     <TargetName="Rebuild">     <!--Take the database offline to disconnect any users. Requires that the current user is an admin of the sql server machine.-->     <MSBuild.ExtensionPack.SqlServer.SqlCmd Variables="@(Variable)" Database="$(DatabaseName)" TaskAction="Execute" CommandLineQuery ="ALTER DATABASE $(DatabaseName) SET OFFLINE WITH ROLLBACK IMMEDIATE"/>         <!--Bring it back online.  If you don't, the database files won't be deleted.-->     <MSBuild.ExtensionPack.Sql2008.DatabaseTaskAction="SetOnline" DatabaseItem="$(DatabaseName)"/>     <!--Delete the database, removing the existing files.-->     <MSBuild.ExtensionPack.Sql2008.DatabaseTaskAction="Delete" DatabaseItem="$(DatabaseName)"/>     <!--Create the new database in the default database path location.-->     <MSBuild.ExtensionPack.Sql2008.DatabaseTaskAction="Create" DatabaseItem="$(DatabaseName)" Force="True"/>         <!--Create admin user-->     <MSBuild.ExtensionPack.SqlServer.SqlCmd TaskAction="Execute" Server="(local)" Database="$(DatabaseName)" InputFiles="$(RebuildDirectory)\0002 Create Admin User.sql" Variables="@(Variable)" />     <!--Create the dbdeploy changelog.-->     <MSBuild.ExtensionPack.SqlServer.SqlCmd TaskAction="Execute" Server="(local)" Database="$(DatabaseName)" LogOn="$(User)" Password="$(Password)" InputFiles="$(RebuildDirectory)\0003 Create Changelog.sql" Variables="@(Variable)" />     <CallTarget Targets="Update;ImportData"/>     </Target>    <TargetName="Update" DependsOnTargets="CreateUpdateScript">     <MSBuild.ExtensionPack.SqlServer.SqlCmd TaskAction="Execute" Server="(local)" Database="$(DatabaseName)" LogOn="$(User)" Password="$(Password)" InputFiles="$(OutputFileName)" Variables="@(Variable)" />   </Target>   <TargetName="CreateUpdateScript">     <ktsc.Build.DBDeploy DbType="mssql"                                        DbConnection="User=$(User);Password=$(Password);Data Source=$(Server);Initial Catalog=$(DatabaseName);"                                        Dir="$(ScriptDirectory)"                                        OutputFile="..\$(OutputFileName)"                                        UndoOutputFile="..\$(UndoFileName)"                                        LastChangeToApply="$(LastChangeToApply)"/>   </Target>     <TargetName="ImportData">     <ItemGroup>       <TestData Include="$(TestDataDirectory)\*.dat"/>     </ItemGroup>     <ExecCommand="$(BCP) $(DatabaseName).dbo.%(TestData.Filename) in&quot;%(TestData.Identity)&quot;$(BCPOptions)"/>   </Target> </Project> Technorati Tags: MSBuild

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  • Crystal Reports Server - Database Login Needs to go Away

    - by Trey Sargent
    The environment I'm working in is a Crystal Reports Server 2008 talking to a MySQL Server 5.1 database using JDBC. The problem is that I get a database logon screen every time I try to access a report from Crystal Reports Server. I've setup a JDBC connection using the MySQL Connector/J driver. When I create a .rpt file I provide the login credentails all is fine. I then publish to InfoView and go to access the report and it prompts me for username and password to the database. I then went to CMC and right-clicked on the report and opened the Database Configuration. I've selected 'Use original database logon information from the report' and 'Use same database logon as when report is run'. However, I still get the logon screen when I try to access the report.

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  • How can you know what is w3wp.exe doing? (or how to diagnose a performance problem)

    - by Daniel Magliola
    I'm having a performance problem in a site we've made, and I'm not exactly sure how to start diagnosing it. The short description is: We have a very small site (http://hearablog.com) with very little traffic, in a crappy dedicated server, CPU is always very high, sometimes it stays at 100% for minutes, and w3wp.exe is taking most of it. A typical scenario is w3wp.exe takes 60%, and SQL Server takes about 30%. Our DB is pretty small too. Long description and more details: The site is hosted in a very crappy server by Cari.Net. From the beginning we had the feeling that the server didn't quite behave correctly, like some things would take just too long, so this could be a configuration problem from the get go. It may also be that we are getting a virtual server while we're supposed to have a dedicated one, although we have no evidence that'd indicate this, except for the fact that the server tends to be quite slow. The server is Windows 2008 Standard 64-bit, with SQL 2008 Express Hardware is a Celeron 2.80 GHz, 1Gb RAM The website is developed in ASP.Net MVC, using Entity Framework for data access. Now, this is pretty crappy hardware, but i've had other servers with these guys, with equivalent (or worse) HW, and performance is much better than this one. That said, the other servers have W2003 and SQL2005, and I'm using ASP.Net "WebForms" 2.0, no MVC, no LINQ, no EF; so I'm not sure whether going to 2008 / the other stuff means a big performance penalty is expected. I'm serving MP3 files (5-20 Mb) regularly, which is a slightly unusual load, maybe that is causing some kind of problems? Would that cause w3wp to use a lot of CPU? Disk usage seems very low. Memory is usually around 90%, but disk usage seems to indicate it's not paging much. I get tons of e-mails every day about SQL timeouts, for queries taking over 30 seconds, although all our queries are pretty straightforward (or should be, but EF may be screwing it up). This is what resource monitor looks like in one of these "sprints" of 100% CPU, in case there's anything useful there. And a snapshot of some performance counters: Now, what confuses me very much is that CPU usage of w3wp is just so high. It shouldn't be doing much really... So my questions are... Is there any way of finding out "what" it is doing? Maybe even profile it? Any performance counters I should be looking at? Is this to be expected given this hardware/software configuration? Is this could be cause by some kind of configuration failure, where would you start looking? Thank you VERY much. Daniel Magliola

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  • The Boss Answer: What is a relational database?

    - by kce
    I'm mostly a system administrator and I don't directly work with databases other than installing them, setting up accounts, granting privileges, and so on. I realized that if The Boss walked up to me and asked, "What is a relational database?" I probably couldn't give a satisfactory answer... I'd maybe mumble something about data being stored and organized by categories which you can query with a special programing language (i.e., SQL). So could someone give a good "Boss Answer" for what a relational database is? And maybe how its different than just storing data on a file server? Bonus points for clever but accessible analogies and explaining tables, columns, records and fields. I'd define a "Boss Answer" as a quick one (maybe two) paragraph explanation for non-technical folks... mostly your Boss, on those rare occasions they actually ask you what it is you do all day.

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  • Using a database class in my user class

    - by Josh
    In my project I have a database class that I use to handle all the MySQL stuff. It connects to a database, runs queries, catches errors and closes the connection. Now I need to create a members area on my site, and I was going to build a users class that would handle registration, logging in, password/username changes/resets and logging out. In this users class I need to use MySQL for obvious reasons... which is what my database class was made for. But I'm confused as to how I would use my database class in my users class. Would I want to create a new database object for my user class and then have it close whenever a method in that class is finished? Or do I somehow make a 'global' database class that can be used throughout my entire script (if this is the case I need help with that, no idea what to do there.) Thanks for any feedback you can give me.

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  • upgrading to worpdress 3.5 erased all posts and pages, wiped database

    - by James
    So I have upgraded to wordpress 3.5 and that seemed to have erased all posts and custom post types, media images, sliders etc' I have made a backup using both pressbackup and backupbuddy but when I try to restore the database (or everything). when it is done, if I look at the front end, everything is back and looks great but then when I go to the back end it says the database needs to be upgraded and doesn't let me bypass that. if i click ok it prompts the following message and after that everything is wiped again: WordPress database error: [Table 'db446353270.wp_categories' doesn't exist] SELECT * FROM wp_categories ORDER BY cat_ID WordPress database error: [Table 'db446353270.wp_post2cat' doesn't exist] SELECT post_id, category_id FROM wp_post2cat GROUP BY post_id, category_id WordPress database error: [Table 'db446353270.wp_linkcategories' doesn't exist] SELECT cat_id, cat_name FROM wp_linkcategories WordPress database error: [Unknown column 'link_category' in 'field list'] SELECT link_id, link_category FROM wp_links please advise. Thanks

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  • Is this slow WPF TextBlock performance expected?

    - by Ben Schoepke
    Hi, I am doing some benchmarking to determine if I can use WPF for a new product. However, early performance results are disappointing. I made a quick app that uses data binding to display a bunch of random text inside of a list box every 100 ms and it was eating up ~15% CPU. So I made another quick app that skipped the data binding/data template scheme and does nothing but update 10 TextBlocks that are inside of a ListBox every 100 ms (the actual product wouldn't require 100 ms updates, more like 500 ms max, but this is a stress test). I'm still seeing ~10-15% CPU usage. Why is this so high? Is it because of all the garbage strings? Here's the XAML: <Grid> <ListBox x:Name="numericsListBox"> <ListBox.Resources> <Style TargetType="TextBlock"> <Setter Property="FontSize" Value="48"/> <Setter Property="Width" Value="300"/> </Style> </ListBox.Resources> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> </ListBox> </Grid> Here's the code behind: public partial class Window1 : Window { private int _count = 0; public Window1() { InitializeComponent(); } private void OnLoad(object sender, RoutedEventArgs e) { var t = new DispatcherTimer(TimeSpan.FromSeconds(0.1), DispatcherPriority.Normal, UpdateNumerics, Dispatcher); t.Start(); } private void UpdateNumerics(object sender, EventArgs e) { ++_count; foreach (object textBlock in numericsListBox.Items) { var t = textBlock as TextBlock; if (t != null) t.Text = _count.ToString(); } } } Any ideas for a better way to quickly render text? My computer: XP SP3, 2.26 GHz Core 2 Duo, 4 GB RAM, Intel 4500 HD integrated graphics. And that is an order of magnitude beefier than the hardware I'd need to develop for in the real product.

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  • Ecommerce Database DNS Switch

    - by KThompson
    Hello, I am moving an e-commerce site to a new server. All has been successful and its time to change the DNS for the domain. It's a relatively popular site and I fear that during propagation orders will be split between the old database and the new one. The databases do contain content that is dependent of the server it is on (Cache path, upload directory, etc.) so I can't just point the old site to the new database. Are there any solutions to this without any of the sites going down. Thanks in advance

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  • Set up Glassfish connection pool to talk to a database on a Ubuntu VPS

    - by Harry Pham
    On my Ubuntu VPS, i have a mysql server running and a Glassfish 3.0.1 Application Server running. And I am having a hard to have my GF successfully ping the database. Here is my GF set up Assume: x.y.z.t is the ip of my VPS Resource Type: javax.sql.ConnectionPoolDataSource User: root DatabaseName: scholar Url: jdbc:mysql://x.y.z.t:3306/scholar URL: jdbc:mysql://x.y.z.t:3306/scholar Password: xxxx PortNumber: 3306 ServerName: x.y.z.t Inside my glassfish3/glassfish/lib, I have my mysql-connector-java-5.1.13-bin.jar Inside the database, table mysql here is the result of the query select User, Host from user; +------------------+-----------+ | User | Host | +------------------+-----------+ | root | 127.0.0.1 | | debian-sys-maint | localhost | | root | localhost | | root | yunaeyes | +------------------+-----------+ Now from my machine, if I try to connect to this db via mysql browser (mysql client software), well I cant. Well from the table above, seem like it only allow localhost to connect to this db. Keep in mind that both my db and my GF are on the same VPS. Please help

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  • Performance of tokenizing CSS in PHP

    - by Boldewyn
    This is a noob question from someone who hasn't written a parser/lexer ever before. I'm writing a tokenizer/parser for CSS in PHP (please don't repeat with 'OMG, why in PHP?'). The syntax is written down by the W3C neatly here (CSS2.1) and here (CSS3, draft). It's a list of 21 possible tokens, that all (but two) cannot be represented as static strings. My current approach is to loop through an array containing the 21 patterns over and over again, do an if (preg_match()) and reduce the source string match by match. In principle this works really good. However, for a 1000 lines CSS string this takes something between 2 and 8 seconds, which is too much for my project. Now I'm banging my head how other parsers tokenize and parse CSS in fractions of seconds. OK, C is always faster than PHP, but nonetheless, are there any obvious D'Oh! s that I fell into? I made some optimizations, like checking for '@', '#' or '"' as the first char of the remaining string and applying only the relevant regexp then, but this hadn't brought any great performance boosts. My code (snippet) so far: $TOKENS = array( 'IDENT' => '...regexp...', 'ATKEYWORD' => '@...regexp...', 'String' => '"...regexp..."|\'...regexp...\'', //... ); $string = '...CSS source string...'; $stream = array(); // we reduce $string token by token while ($string != '') { $string = ltrim($string, " \t\r\n\f"); // unconsumed whitespace at the // start is insignificant but doing a trim reduces exec time by 25% $matches = array(); // loop through all possible tokens foreach ($TOKENS as $t => $p) { // The '&' is used as delimiter, because it isn't used anywhere in // the token regexps if (preg_match('&^'.$p.'&Su', $string, $matches)) { $stream[] = array($t, $matches[0]); $string = substr($string, strlen($matches[0])); // Yay! We found one that matches! continue 2; } } // if we come here, we have a syntax error and handle it somehow } // result: an array $stream consisting of arrays with // 0 => type of token // 1 => token content

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  • agent-based simulation: performance issue: Python vs NetLogo & Repast

    - by max
    I'm replicating a small piece of Sugarscape agent simulation model in Python 3. I found the performance of my code is ~3 times slower than that of NetLogo. Is it likely the problem with my code, or can it be the inherent limitation of Python? Obviously, this is just a fragment of the code, but that's where Python spends two-thirds of the run-time. I hope if I wrote something really inefficient it might show up in this fragment: UP = (0, -1) RIGHT = (1, 0) DOWN = (0, 1) LEFT = (-1, 0) all_directions = [UP, DOWN, RIGHT, LEFT] # point is just a tuple (x, y) def look_around(self): max_sugar_point = self.point max_sugar = self.world.sugar_map[self.point].level min_range = 0 random.shuffle(self.all_directions) for r in range(1, self.vision+1): for d in self.all_directions: p = ((self.point[0] + r * d[0]) % self.world.surface.length, (self.point[1] + r * d[1]) % self.world.surface.height) if self.world.occupied(p): # checks if p is in a lookup table (dict) continue if self.world.sugar_map[p].level > max_sugar: max_sugar = self.world.sugar_map[p].level max_sugar_point = p if max_sugar_point is not self.point: self.move(max_sugar_point) Roughly equivalent code in NetLogo (this fragment does a bit more than the Python function above): ; -- The SugarScape growth and motion procedures. -- to M ; Motion rule (page 25) locals [ps p v d] set ps (patches at-points neighborhood) with [count turtles-here = 0] if (count ps > 0) [ set v psugar-of max-one-of ps [psugar] ; v is max sugar w/in vision set ps ps with [psugar = v] ; ps is legal sites w/ v sugar set d distance min-one-of ps [distance myself] ; d is min dist from me to ps agents set p random-one-of ps with [distance myself = d] ; p is one of the min dist patches if (psugar >= v and includeMyPatch?) [set p patch-here] setxy pxcor-of p pycor-of p ; jump to p set sugar sugar + psugar-of p ; consume its sugar ask p [setpsugar 0] ; .. setting its sugar to 0 ] set sugar sugar - metabolism ; eat sugar (metabolism) set age age + 1 end On my computer, the Python code takes 15.5 sec to run 1000 steps; on the same laptop, the NetLogo simulation running in Java inside the browser finishes 1000 steps in less than 6 sec. EDIT: Just checked Repast, using Java implementation. And it's also about the same as NetLogo at 5.4 sec. Recent comparisons between Java and Python suggest no advantage to Java, so I guess it's just my code that's to blame? EDIT: I understand MASON is supposed to be even faster than Repast, and yet it still runs Java in the end.

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  • What are appropriate ways to represent relationships between people in a database table?

    - by Emilio
    I've got a table of people - an ID primary key and a name. In my application, people can have 0 or more real-world relationships with other people, so Jack might "work for" Jane and Tom might "replace" Tony and Bob might "be an employee of" Rob and Bob might also "be married to" Mary. What's the best way to represent this in the database? A many to many intersect table? A series of self joins? A relationship table with one row per relationship pair and type, where I insert records for the relationship in both directions?

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  • Web service performance testing plan, Microsoft .NET WS, SQL

    - by zxed
    Trying to answer a question to come up with a testing plan. It has to do with using a website and/or webservice that queries a sql server to get data and display to user. * Solution must be able to handle an estimated 2000 users, approximately 700 concurrent users, 10,000 + website hits a month. Database calls should handle 100,000 queries via the website/webservice a month. The system is used at multiple times during a 24 hour period; however networking and bandwidth traffic decreases after 5 pm * two windows 2003 servers are used, one for web, another for sql. Both are located in the same room. User access is varied and users can be far/near (its a centralized system), users access via www

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  • Convert a MSSQL database to MYSQL database

    - by soldieraman
    Alright so I want to convert an already exist MSSQL database (2005) to a MYSQL database. There is nothing extraordinary to be done The only things I need to achieve is Recreate the tables Transfer data Relationships would be nice but not necessary No views, no sprocs, no functions. Any easy way to do this. Also do you know of any DST (Database Synchronization Tool) which would let me do MSSQL to MYSQL MYSQL to MYSQL MSSQL to MSSQL (I know there is SQL Delta for this)

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  • Command line import of database using latin1 encoding

    - by chrisjlee
    I'm using a particular cloud hosting solution (one which i won't name) and they don't provide ssh access so i'm at a whim on how the database is dumped. I downloaded the dump which is packed into a tar.gz file. I discover that this file utilizes latin1 encoding. Which i don't get to specify the encoding for the host i'm using because i don't have SSH access or DB access. I try to import it via command line for my local development environment (mysql -uroot foodb < file.db) like i usually do with other databases but am having problems. Is it possible to import a database via command line by specifying which encoding (preferably latin1) before importing it? Or do i have to convert it to UTF8?

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  • Performance Optimization for Matrix Rotation

    - by Summer_More_More_Tea
    Hello everyone: I'm now trapped by a performance optimization lab in the book "Computer System from a Programmer's Perspective" described as following: In a N*N matrix M, where N is multiple of 32, the rotate operation can be represented as: Transpose: interchange elements M(i,j) and M(j,i) Exchange rows: Row i is exchanged with row N-1-i A example for matrix rotation(N is 3 instead of 32 for simplicity): ------- ------- |1|2|3| |3|6|9| ------- ------- |4|5|6| after rotate is |2|5|8| ------- ------- |7|8|9| |1|4|7| ------- ------- A naive implementation is: #define RIDX(i,j,n) ((i)*(n)+(j)) void naive_rotate(int dim, pixel *src, pixel *dst) { int i, j; for (i = 0; i < dim; i++) for (j = 0; j < dim; j++) dst[RIDX(dim-1-j, i, dim)] = src[RIDX(i, j, dim)]; } I come up with an idea by inner-loop-unroll. The result is: Code Version Speed Up original 1x unrolled by 2 1.33x unrolled by 4 1.33x unrolled by 8 1.55x unrolled by 16 1.67x unrolled by 32 1.61x I also get a code snippet from pastebin.com that seems can solve this problem: void rotate(int dim, pixel *src, pixel *dst) { int stride = 32; int count = dim >> 5; src += dim - 1; int a1 = count; do { int a2 = dim; do { int a3 = stride; do { *dst++ = *src; src += dim; } while(--a3); src -= dim * stride + 1; dst += dim - stride; } while(--a2); src += dim * (stride + 1); dst -= dim * dim - stride; } while(--a1); } After carefully read the code, I think main idea of this solution is treat 32 rows as a data zone, and perform the rotating operation respectively. Speed up of this version is 1.85x, overwhelming all the loop-unroll version. Here are the questions: In the inner-loop-unroll version, why does increment slow down if the unrolling factor increase, especially change the unrolling factor from 8 to 16, which does not effect the same when switch from 4 to 8? Does the result have some relationship with depth of the CPU pipeline? If the answer is yes, could the degrade of increment reflect pipeline length? What is the probable reason for the optimization of data-zone version? It seems that there is no too much essential difference from the original naive version. EDIT: My test environment is Intel Centrino Duo processor and the verion of gcc is 4.4 Any advice will be highly appreciated! Kind regards!

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  • Optimising Database Calls

    - by Dwaine Bailey
    I have a database that is filled with information for films, which is (in turn) read in to the database from an XML file on a webserver. What happens is the following: Gather/Parse XML and store film info as objects Begin Statement For every film object we found: Check to see if record for film exists in database If no film record, write data for film Commit Statement Currently I just test for the existence of a film using (the very basic): SELECT film_title FROM film WHERE film_id = ? If that returns a row, then the film exists, if not then I need to add it... The only problem is, is that there are many many hundreds of records in the database (lots of films!) and because it has to check for the existence of a film in the database before it can write it, the whole process ends up taking quite a while (about 27 seconds for 210 films) Is there a more efficient method of doing this, or just any suggestions in general? Programming Language is Objective-C, database is in sqlite3 Thanks, Dwaine

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  • Postgres: clear entire database before re-creating / re-populating from bash script

    - by Hoff
    hi folks, I'm writing a shell script (will become a cronjob) that will: 1: dump my production database 2: import the dump into my development database Between step 1 and 2, I need to clear the development database (drop all tables?). How is this best accomplished from a shell script? So far, it looks like this: #!/bin/bash time=`date '+%Y'-'%m'-'%d'` # 1. export(dump) the current production database pg_dump -U production_db_name > /backup/dir/backup-${time}.sql # missing step: drop all tables from development database so it can be re-populated # 2. load the backup into the development database psql -U development_db_name < backup/dir/backup-${time}.sql Many thanks in advance! Martin

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  • Cloud Database Service Latency/Performance

    - by Gcoop
    Hi All, I am running a heavy traffic site and our server is beginning to get to its limits, at the moment the entire LAMP stack is on one box (not ideal). I would like to move the database onto it's own box or onto a cloud service, but from my previous experience moving the database off the same box as the webserver increases the latency of reads quite dramatically slowing down the site. Is using a cloud service for this going to overcome this problem, because as far as I can tell its essentially the same situation (as moving it onto a separate box in my control)? In which case why is there so much popularity around cloud based database services at the moment? Are cloud based database services so quick that the latency of reads is so low that its almost like having it on the same box in the same datacentre?

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  • Cannot start Oracle XE 11gR2 Net Listener and Database on Ubuntu 13.04

    - by hydrology
    I have been following the setup step on this article for installing Oracle XE 11g R2 on Ubuntu 13.04. The environment variables PATH, ORACLE_HOME, ORACLE_SID, NLS_LANG ORACLE_BASE have all been set up correctly. simongao:~ 06:16:38$ echo $PATH /usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/home/simongao/adt-bundle-linux-x86_64-20130219/sdk/platform-tools:/u01/app/oracle/product/11.2.0/xe/bin simongao:~ 06:18:36$ echo $ORACLE_HOME /u01/app/oracle/product/11.2.0/xe simongao:~ 06:23:29$ echo $ORACLE_SID XE simongao:~ 06:23:35$ echo $ORACLE_BASE /u01/app/oracle simongao:~ 06:23:37$ sudo echo $LD_LIBRARY_PATH /u01/app/oracle/product/11.2.0/xe/lib simongao:~ 06:23:48$ echo $NLS_LANG /u01/app/oracle/product/11.2.0/xe/bin/nls_lang.sh However, when I try to startup the service, I receive the following error information. simongao:~ 06:18:40$ sudo service oracle-xe start Starting Oracle Net Listener. Starting Oracle Database 11g Express Edition instance. Failed to start Oracle Net Listener using /u01/app/oracle/product/11.2.0/xe/bin/tnslsnr and Oracle Express Database using /u01/app/oracle/product/11.2.0/xe/bin/sqlplus.

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